The junior senator from Kentucky is now getting some much-needed rest.

Libertarian Republican senator Rand Paul, the son of wannabe Republican presidential nominee Ron Paul, made history last night with one of the longest filibuster speeches in American history. Paul spoke for thirteen hours in an attempt to delay the senate confirmation of John Brennan to run the CIA, making a case against the President's equivocation on whether or not it is legitimate to carry out drone strikes on American citizens on American soil.

The filibuster has become a standard part of Senate republican blocking tactics in recent years, in part because its meaning has changed over time. It used to be the case that to filibuster a debate meant to speak at length in order to prevent it coming to a vote, with the intention being that the Senate would run out of time and have to move on to other business.

It was in that climate that Strom Thurmond made the longest ever filibuster speech during the debate over the 1957 civil rights act, speaking for 25 hours straight against the bill. (The fact that Thurmond's marathon effort was in support of racism didn't play against him, and he went on to become the oldest and longest-serving senator in US history, switching allegiance to the Republican party in 1964 and only retiring in 2003.)

Thurmond's attempt failed because the Senate authorities were prepared to delay all future discussions until the civil rights act passed. But in recent years, merely the threat of a filibuster has been enough to cause a bill to be abandoned. Since a vote of "cloture"—a motion to end the debate and move to a vote—requires a supermajority of sixty of the hundred senators, this has the effect of meaning that the minority party, provided it has more than forty senators, can control the Senate.

Earlier in the same session, Paul had joined in with this more common style of filibustering, refusing a vote of cloture for a judicial nominee who had once sued a gun company. But taking a stand agains Brennan, he did it the old-fashioned way, speaking passionately for thirteen hours on the problems with extrajudicial killing of Americans.

Frequently in filibusters, in the US and elsewhere, the delaying tactics are transparent. Legislators have even been known to read the contents of the phonebook in an attempt to find something to say, and one memorable case in Canada involved an MP reading the entirety of his own book to the parliament. Since the Canadian Hansard is bilingual, he was accused of receiving a taxpayer-funded translation on purpose.

Sen. Ron Johnson of Wisconsin gave a speech as much about the dysfunctional Senate and the dangers of the national debt as about drone policy. Sen. Tim Scott of South Carolina said that the essential issue of liberty shouldn’t divide the political parties. Sen. Jeff Flake of Arizona told Paul “the question you’ve asked is totally right and proper.” And so on.

As Ezra Klein points out, the success of Paul's filibuster—it was the first-term senator's biggest moment in the legislature to date, and succeeded in making his objections stand out from the normal Republican obstructionism—shows that there are times when the filibuster is a positive contribution to the machinations of the Senate. Klein writes:

This is the highest purpose of the filibuster: Allowing a passionate minority to slow down the Senate and make their case to both their colleagues and the American people. If more filibusters went like this, there'd be no reason to demand reform. And if there is reform, it needs to hold open the possibility for filibusters like this.

Eventually, nature took its course and Paul retired from the chamber, ending his speech with a note of regret that Thrumond's achievement still stands:

I would try to go another 12 hours and try to break Strom Thurmond’s record, but there are some limits to filibustering and I am going to have to go take care of one of those here.